That’s the snapshot revealed by almost 240 comments sent to the Office of Personnel Management on its draft rules for implementing the landmark change to federal retirement regulations approved by Congress last year.

Under OPM’s draft plan — which ran 28 triple-columned pages when published three months ago in the Federal Register — employees who are eligible for retirement and meet other requirements could work half-time while getting half of their pension. As they continue to work, phased retirees also will keep accruing additional service credit toward their final pensions.

While on the job, they will have to spend 20 percent of their time in “mentoring activities,” ideally with the employees who will take over for them when they completely retire.

The public comments show active employees eagerly embracing the possibility of a part-time retirement.

“I would like to know when this will start and how to go about signing up,” one Social Security Administration employee wrote.

“At this stage in my life, phased retirement would be perfect for me,” said a Veterans Affairs Department worker with more than 30 years of service.

Many employees are pressing OPM to make it easier to qualify for the program.

But HR professionals, while sometimes supportive of the concept, posed an array of nuts-and-bolts questions about how the new program will work in practice.

Implementation will mean more demand for agency support services, such as the need to retire employees twice, Kathleen Hutson, associate director for human resources at the National Security Agency, said in a memo.

“Given the related impact on OPM resources, should agencies expect an increase in the time for OPM to adjudicate annuities?” Hutson asked.

The Smithsonian Institution in its comments to OPM said the details surrounding phased retirement will be “complex and cumbersome.”

A Defense Department manager wanted to know whether an employee could take a buyout and still qualify.

OPM is still reviewing comments on the draft rules, spokesman Edmund Byrnes said. The agency has given no indication on when it will issue final rules.

Henry Romero, a former OPM executive, said he understood the trepidation among federal human resources officials at adding to a thicket of already complex federal pay and retirement rules.

“There are just so many variations” affecting individual employees’ retirement eligibility, said Romero, a senior adviser at Federal Management Partners, a consulting firm. “You’ve got to have adequate controls in place and very clear guidance to agency managers, so that the benefit is used as the Congress intended.”

Implementation “is going to be a bit of a pain administratively, but it’s certainly manageable,” said John Palguta, vice president for policy at the Partnership for Public Service.

With a retirement-driven brain drain potentially ahead, the prospect of letting seasoned staff share expertise with younger colleagues was a key selling point after the Obama administration proposed phased retirement last year.

What that would mean in practice, however, is “vague,” Carol Bonosaro, president of the Senior Executives Association, wrote in her comments. The group, which represents career Senior Executive Service members, urged OPM to write specific guidelines into the final regulations “to help ensure that this new mentoring requirement is taken seriously.”

The National Treasury Employees Union, on the other hand, wants agencies to have more latitude to waive the requirement when they lack the money to hire new staff “because it may not be practical for the phased retiree to mentor an individual to replace him or her.”

Phased retirement would not be an entitlement; cops, air traffic controllers and other employees subject to mandatory retirement wouldn’t qualify. Even for eligible applicants, agencies would have to approve their requests to go to part-time status, prompting the NTEU to urge creation of an appeal route for those who are turned down.

And while the plan makes clear that phased retirees will be treated as regular employees for purposes of participating in the Federal Employees Health Benefits Program, it says nothing about eligibility for dental, vision and long-term care insurance, the union said.

The plan also is silent about phased retirees’ ability to take money out of their Thrift Savings Plan accounts. But because they are still legally considered federal employees, the same withdrawal restrictions that apply to full-time workers remain in force, said Kim Weaver, a spokeswoman for the TSP board.

Even before OPM issues the final regulations, it’s facing pressure to ease service requirements. Under the draft plan, for example, a Federal Employees Retirement System participant would need at least 20 years of service at age 60 or 30 years of service at the minimum retirement age, which ranges from 55 to 57, depending on date of birth.

In its comments, the Smithsonian Institution argued that a 62-year-old with five years of government service should be eligible. In a separate filing, a 75-year-old National Institutes of Health employee with 18 years of service also wanted the chance to take advantage of phased retirement.

“In this financial climate, it is important for us to have that option and not feel discriminated against,” the employee wrote.